FIELD OF THE INVENTION
The invention relates to an electric plug-in connector, including a trough-shaped socket unit and a plug unit being fittingly insertable into the socket unit; the socket unit having a plug channel with an elongated, approximately rectangular cross section being defined by longer longitudinal side walls and shorter transverse side walls and being closed off at an inner end thereof by a bottom from which a multiplicity of plug pins protrude at right angles; the plug channel of the socket unit having recesses in the longitudinal side walls defining a clear opening or enlarged internal diameter approximately in a middle region; the plug unit having a substantially rectangular cross section with longitudinal lateral surfaces, transverse lateral surfaces and a front closure surface in which insertion openings are formed for the passage of the plug pins therethrough to plug sockets located behind them; the transverse lateral surfaces being guided along the transverse side walls and the longitudinal lateral surfaces being guided on guide segments of the longitudinal side walls, upon insertion of the plug unit into the socket unit; respective safety ribs extending in the insertion direction in the vicinity of two end edges on both longitudinal lateral surfaces of the plug unit; and complementary safety grooves being formed in the longitudinal side walls of the socket unit in the vicinity of two end edges for receiving the safety ribs.
Such a plug-in connector is known from U.S. Pat. No. 4,376,565.
In multiple-plug connectors it is known to provide encoding in a plug housing to prevent them from being plugged in the wrong way. To that end, an encoding rib is formed onto one part, for instance the plug unit, while a complementary encoding groove is provided in the respectively other part, in that case the socket unit. In such a case, the plug unit can be introduced into the socket unit only with a predetermined alignment, on the condition that the latter has a corresponding encoding groove.
However, such encoding merely prevents the two plug units from being inserted all the way into one another with their alignment reversed or with different encoding, which would produce incorrect electrical connections. However, often the encoding cannot prevent the plug unit from being introduced partway into the plug channel. In particular, if an encoding rib is mounted on one end of the plug unit, the other end of the plug unit can be pressed crooked into the plug channel, where it will damage or bend the plug pins. That may conceivably happen, for instance, when the plug is installed in poorly accessible places with poor visibility, such as inside motor vehicles. Introducing the plug unit into the plug channel crookedly by mistake can cause the aforementioned damage to the plug pins, which in turn entails expensive repair work involving replacement of the parts.